#include<iostream>
#include<algorithm>
#include<iomanip>
using namespace std;
int main()
{
	int n;
	cin >> n;
	double fz = 1.0, fm = 1.0, sum = 0.0;
	sum += fz / fm;
	fm++;
	for (int i = 2; i <= n; i++)
	{
		fz = -1 * fz;
		sum += fz / fm;
		fm++;
	}
	cout << fixed << setprecision(4) << sum << endl;
	return 0;
}